1. Field of the Invention
The present invention relates to a plasma processing method forming an insulating film on the surface of a substrate by using plasma, a plasma processing apparatus for performing the plasma processing method, and a computer recording medium.
2. Description of the Related Art
As an insulating film formed on a silicon substrate, a thermal oxide film formed by performing oxidation processing at high temperature of 1000° C. or higher has been often used conventionally. As microfabrication technology advances in recent years, it becomes necessary to reduce the thickness of this kind of oxide film (insulating film) in which reaction of Si and O progresses only by thermal energy.
However, according to the formation method of the insulating film by thermal oxidation processing at high temperature, a leakage current and the like increase as the thickness decreases and it is difficult to obtain the insulating film with high reliability. Further, a nonvolatile memory which performs reading and writing by passing a current through the insulating film has the problem of deterioration in its memory characteristic due to holes or electrons trapped in the insulating film. It is considered that the hole traps particularly affect reliability of a product.
In order to solve the above problem, oxidation processing by active atomic oxygen (hereinafter referred to as the “oxygen radical”) using plasma, whose reaction mechanism is different from that of the thermal oxidation method, has been realized. According to this method, it is possible to form the oxide film while electron temperature of the plasma is kept at low temperature, which results in reducing damages to the substrate to be processed and an inner wall of a processing apparatus. Further, since the hole traps are reduced, it becomes possible to form the thin oxide film without affecting the reliability.
Japanese Patent Application No. Tokukai-Hei 11-293470 discloses the formation method of the oxide film using the plasma. This is a method of forming a silicon oxide film by introducing a silicon-containing gas and an oxygen-containing gas into a process chamber, and generating plasma of these gases, to deposit the silicon oxide film on the substrate. Besides the aforesaid silicon-containing gas and the oxygen-containing gas, a hydrogen gas is introduced into the process chamber to generate the plasma containing hydrogen in the process chamber. Thereby, it is possible to obtain the excellent film quality equivalent to the thermal oxide film.